Haruka, a teacher in charge of the badminton club, was having an affair with her colleague Ishida. Although they started dating without knowing that Ishida had a family, the relationship continued even after they found out...Haruka became a convenient woman. One day, a student, Yoshii, witnessed this 'relationship that should not be known to anyone'. When Yoshii found out that his beloved Haruka was having an affair, he used it as an excuse to force Haruka into a physical relationship.